Abstract:

Accurate total-energy pseudopotential methods are used to study the structures, binding energies, and local vibrational modes of various models for the Ga-O-Ga defect in GaAs. We find that the previously proposed models, OAs (an off-centered substitutional oxygen in arsenic vacancy) and OI (an oxygen atom occupying a tetrahedral interstitial site), are inconsistent with experimental data. We introduce a model, (AsGa)2−OAs (two arsenic antisites and one off-centered substitutional oxygen in arsenic vacancy), the properties of which are in excellent agreement with experimental characterizations.